Phosphate esters are finding increasing use as fire resistant lubricating and hydraulic fluids. These ester lubricants have the desirable properties of low flammability, high lubricity, and long service life.
New machinery or machinery in storage or transport is sometimes rustproofed with conventional petroleum based compositions or other formulations which are not compatible with phosphate esters. The use of these petroleum based products often necessitates an extensive cleaning before machinery may be operated with phosphate ester fluids.
An important use of rust preventive compositions is in machinery which is in storage or is inactivated for servicing. U.S. Pat. No. 4,263,062 describes a phosphate ester based composition effective in preventing corrosion where the composition contacts metal surfaces.
A shortcoming of the rust preventive composition of U.S. Pat. No. 4,236,062 is that it exhibits its rust preventive properties only when in contact with metal surfaces. Unfortunately, machinery in storage or disuse may have many internal areas that do not permit inspection or access and where the rust preventive fluid has drained off or failed to make contact.